Add timeline mermaid diagram for core team

[jfy133]

Because we :metal:

@netlify /about/governance

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[jfy133]

@nf-core-bot fix linting

[jfy133]

I'm not sure how to make the font size bigger, nor to stop the overlaps of names over the bars... but I'll let it bother someone else and make them fix it ;)

[christopher-hakkaart]

I do love a good graph, but it is very small. Additionally, I wonder if this information is superfluous to the page's purpose, which is primarily to describe the teams, their responsibilities, and list their members.

Would it be better to have another section on the profile button, showing 2018-2025 or whatever? Maybe bury the graph in a dropdown?